That is because they have no actual humor.
They sneer, jeer and snark.
Which can be a part of humor but not the entire package.
Humor is being able to laugh at yourself as well as at others.
That’s right. They can’t take a joke and they can’t even see one. Tell a joke about them and they shout insurrection, terrorism, racism! Then they sue you or get the FBI to track you. Next thing you know, you’re sitting in front of Pelosi’s congressional inquisition.